Electronic sewing machine

ABSTRACT

A sewing machine has a rotatable shaft for operating a stitch forming device, and includes a feed dog for feeding fabric to be sewn, and a needle for forming stitches in the fabric. The machine comprises a first electronic memory for storing stitch control data and including at least the needle position control data for different patterns; pattern selecting element for reading the first memory stitch control data for a selected pattern; timing element operated synchronously with the shaft to produce a timing signal for progressively reading the stitch control data from the first memory; stitch mode changing switch element for determining an elongation rate of a selected pattern to be elongated in a fabric feeding direction; second memory element for temporarily storing designated stitch control data of the first memory element; counter element for counting the ordinals of the stitches of the selected pattern in relation to the timing signals and in accordance with the pattern elongation rate to thereby designate the pattern elongation rate and the stitch control data to be stored into the second memory element progressively during formation of the stitches of the pattern; and calculating element operable with respect to the counter element (CT1, CT2) to make a calculation to produce second stitches between the first stitches formed by the stitch control data.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an electronic sewing machine having a memory unit for storing stitch control data for different patterns, which are selectively and progressively read out to control the stitch forming device of the sewing machine to produce a selected pattern of stitches. More particularly the invention relates to an electronic sewing maching having a device including a control circuit which is operated to control the needle positions for the purpose of modifying the stitches of a selected pattern, to thereby elongate the pattern in the fabric feeding direction with a constant feeding pitch and with a predetermined elongation rate.

2. Description of the Prior Art

The conventional pattern elongation device has been used in the sewing machine having a cam-type pattern generating mechanism to elongate a selected pattern in the fabric feeding direction with a constant feeding pitch by way of effectively adjusting transmission relation between the pattern cam and the needle control device. However, such prior art pattern elongation devices are mechanically complicated and are impractical to use. to elongate various patterns and has Heretofore, an electronic sewing machine having an electronic memory for storing stitch control data for controlling the stitch forming device of the sewing machine are generally unknown.

SUMMARY OF THE INVENTION

The present invention has been provided to eliminate the defects and disadvantages of the prior art, by providing an electronic sewing machine having a memory for storing stitch control data which are progressively read out to control the stitch forming device of the sewing machine to form a basic pattern. According to the invention, the number of stitches to be formed between the adjacent stitches of the original pattern are determined by the stitch control data of the adjacent stitches. Then a memorized calculation formula is applied with the stitch control data defining the space between the adjacent stitches, the stitch coordinate changing inclination, and the data representing the number of stitches, and the ordinals thereof to be formed between the adjacent stitches. Thus, new stitch control data are calculated to control the needle of the sewing machine which was originally controlled by the stitch control data stored in the memory. In this way, a selected pattern is elongated in the feeding direction with a predetermined elongation rate and with a constant feeding pitch.

BRIEF DESCRIPTION OF DRAWINGS:

FIG. 1 illustrates a pattern to be elongated by the present invention with a predetermined elongation rate;

FIG. 2 is the pattern of FIG. 1 to be elongated by the present invention with a different predetermined elongation rate;

FIGS. 3A and 3B block diagrams which together illustrate a a preferred embodiment of a contral circuit of the present invention; and

FIG. 4 is a time chart showing the operation times of the circuit components with the output and triggering signal lenses thereof.

DETAIL DESCRIPTION OF THE INVENTION

In reference to FIGS. 1 and 2, there is shown a pattern produced in accordance with the invention, a series of stitch coordinates A, B, C . . . J are produced by the stitch control data stored in an electronic memory with a constant fabric feeding pitch. In FIG. 1, if the stitch coordinates N, O, P are calculated out, for examples, between the stitch coordinates C and D instead of the stitch coordinate D with the same amount of feeding pitch as with the stitch coordinates A, B, C . . . J, the pattern can be elongated such that it is twice long as the pattern of stitch coordinates A, B, C . . . J. According to the invention, the stitch coordinate N is calculated from the stitch coordinates B and D, the stitch coordinate O is calculated from the stitch coordinates C and E, and the stitch coordinate P is calculated from the stitch coordinates D and F. For example, stitch coordinates C, N, O, P, E are shown with a feeding pitch approximately equal to one half of the feeding pitch of the stitch coordinates A, B, C . . . J. FIG. 2 shows the same pattern of FIG. 1 which is to be elongated as aforesaid, such that it is three times as long as the pattern of stitch coordinates A, B, C . . . J.

Referring to FIGS. 3A and 3B, ROM is an electronic static memory for storing the stitch control data for controlling a needle of a sewing machine to the stitch coordinates A, B, C . . . J, as is shown in FIGS. 1 and 2. PS is a pattern selecting device including a number of pattern selecting switches selectively operated to a pattern signal for addressing the initial address of the memory ROM. The addresses of the memory ROM are sequentially advanced to read out the stitch control data at the output A1 thereof with a timing pulse generated by a pulse generator SY operated in synchronism with rotation of an upper drive shaft of the sewing machine not herein shown. CT₁ is a counter which is reset at the time of application of a control power source or at the time of a pattern selection. If stitch mode changing switch SW is operated to select a pattern elongation, the counter CT₁ renders one of the outputs Q₀ -Q₄ high level progressively from the output Q₀ a per stitch of a pattern while rendering the others a low level. If the high level goes to a predetermined one of the outputs Q₀ -Q₄, the counter CT₁ is reset through an AND circuit AN₁ or AN₂ and through an OR circuit OR₁, and as the result, the initial output Q₀ becomes a high level. Thus, the ordinals of stitches are determined.

The stitch mode changing switch SW has a movable contact (e) connected to a timing signal generating device SY through an AND circuit AND₃ which is operated to make effective the signal of the timing signal generating device SY when a machine controller switch CONT is closed. The stitch mode changing switch has a fixed contact (a₁). If the fixed contact (a₁) is in engagement with the movable contact (e), the stitches A-J in FIGS. 1 and 2 are produced in accordance with the stitch control data stored in the memory ROM. Namely, the fixed contact (a₁) is connected to the reset terminal RS of the counter CT₁ through the OR circuit OR₁, and the high level signal at the reset terminal RS resets the counter CT₁. The stitch mode changing switch SW has another fixed contact (a₂). If the fixed contact (a₂) is in engagement with the movable contact (e), the stitches illustrated by a solid line in FIG. 1 are produced. in FIG. 1. Namely, a pattern is produced that is elongated twice as long as the original pattern. The fixed contact (a₂) is connected to one input of the AND circuit AN₁. The stitch mode changing switch SW has another fixed contact (a₃) connected to one input of the AND circuit AN₂. As is shown in FIG. 2, If the fixed contact (a₃) is in engagement with the movable contact (e), the stitches illustrated by the solid line are produced. Namely, a pattern is produced that is elongated about three times as long as the original pattern.

The AND circuits AN₁ and AN₂ have the other inputs connected to the output terminals Q₄, Q₃ of the counter CT₁, respectively. Each time the output Q₄, or Q₃ becomes a high level, the counter CT₁ is reset and the output Q₀ is rendered a high level. It is therefore possible, as is mentioned hereinafter, to reset the counter CT₁ after a desired number of stitches are produced so as to determine the stitches between the basic stitches, for example, between the stitches B and D or D and F shown in FIGS. 1 and 2, to thereby determine the pattern elongation rate of a pattern.

The counter CT₁ has a trigger terminal C_(p) connected to an AND circuit AN₄ so that the counter may advance counting at the high level signal of the timing signal generating device SY. The timing signal generating device SY is designed to produce a timing signal which is turned to a high level after a needle of the sewing machine (not shown) comes out of a fabric to be sewn and is turned to a low level just before the needle penetrates the fabric. CT₂ is a ring counter which is reset at the time of application of the control power source or at the time of a pattern selection. MM is a monostable multivibrator circuit which is operated by way of an AND circuit AN₅ or AN₆ and by way of OR circuits OR₂, OR₃, OR₄, when the movable contact (e) of the stitch mode changing switch SW is in engagement with the fixed contact (a₂) or (a₃) and the output Q₀ is a high level and the controller switch CONT is closed. When a low level signal of the monostable multivibrator circuit MM is applied to the trigger terminal of the counter CT₂, the counter CT₂ turns the output Q₀ to a low level from a high level and the output Q₁ to a high level, to thereby maintain the operation of the monostable multivibrator circuit MM through the OR circuits OR₄, OR₅. Subsequently, the counter CT₂ turns one of the outputs Q₂ -Q₅ to a high level progressively while turning the others to a low level.

The counter CT₂ has a reset terminal RS connected to the output Q₀ of the counter CT₁, and is reset by the high level signal at the output Q₀. When the movable contact (e) of the stitch mode changing stitch SW is in engagement with the fixed contact (a₁), the counter CT₂ is not operated by way of the AND circuits AN₅ and AN₆. The function of the counter CT₂ is to read out a plurality of stitch control data from the memory ROM for a single stitch and to selectively the read out stitch control data to a stitch forming device DV of the sewing machine, or to read out a plurality of the stitch control data from the memory ROM for a single stitch and give the read out data to a calculating device AR₁ which calculates a new stitch control data from the given stitch control data. The memory ROM is addressed to produce a stitch control data A₁ at the designated address together with an address signal A₂ for designating the next address. Another calculating device AR₂ receives the address signal A₂ and is operated by a high level signal at any of the outputs Q₁ -Q₄ of the counter CT₂, which signal is applied to the trigger terminal C_(p) of the calculating device AR₂ to make a calculation for advancing the address of the memory by one. The output of the calculating device AR₂ is applied to a pattern data read-out device DR through a tristate buffer G₁, the gate of which is opened by the same high level output signal of the counter CT₂.

The pattern data read-out device DR has a trigger terminal C_(p) receiving, through an OR circuit OR₆, a trigger signal at a time a little later than the calculating device AR₂ to transmit the output signal of the calculating device AR₂ to the memory ROM as an address signal. Dn-1, Dn, Dn+1 Dn+2, Dn+3 are latch circuits, that is to say temporary electronic memories, each have a trigger terminal C_(p) for receiving a low level signal to latch the stitch control data A₁ of the memory ROM. The latch circuit Dn-1 receives the trigger signal through an AND circuit AN₇, and latches the stitch control data A₁ when the output Q₀ of the counter CT₂ is changed to a low level from a high level immediately after the monostable multivibrator circuit MM becomes inoperative. The latch circuits Dn-Dn+3 progressively latch the stitch control data A₁ which are progressively read out from the memory ROM as the addresses of the memory ROM are progressively advanced by way of the calculating device AR₂ while the outputs Q₁ -Q₄ are turned to a low level from a high level.

G₂, G₃ and G₄, G₅ and G₆, G₇, and G₈ are tristate buffers receiving the outputs from the latch circuits Dn-1 to Dn+3, respectively, and having trigger terminals C_(p), respectively, which are turned to a high level to open the gates of the respective buffers. The output of the buffer G₃ is connected to a latch circuit L₁, the outputs of the buffers G₂, G₄, G₅ are connected to a latch circuit L₂, and the outputs of the buffers G₆, G₇, G₈ are connected to a latch circuit L₃. The latch circuits L₂, L₃, upon receiving a trigger signal at the trigger terminal C_(p) thereof, latch the outputs of the buffers to give the same outputs to the calculating device AR₁. The calculating device AR₁, upon receiving a high level signal at the trigger terminal thereof, gives the calculated output to the latch circuit L₁ through a tristate buffer G₉. The latch circuit L₁, upon receiving a high level signal at the trigger terminal thereof, gives the stitch forming device the output of the latch circuit Dn or the output of the calculating device AR₁.

Ke is constant generating device having the inputs 1/4, 1/2, 3/4, 1/3, 2/3, one of which is selectively rendered a high level to give the corresponding constant to the calculating device AR₁. The calculating device AR₁ makes a calculation Ke (L₃ -L₂)+L₂ from the outputs of the constant generating device Ke and of the latch circuits L₂, L₃ to determine the stitch coordinates K-Z shown and K'-Z' in FIGS. 1 and 2, and gives the output to the latch circuit L₁. AND circuits AN₈ -AN₁₆ and OR circuits OR7-OR9 designate one of the inputs of the constant generating device Ke in response to the operation of the counter CT, which depends upon the operation of the stitch mode changing switch SW. Flip-flop circuits FF₁, FF₂ are so connected so as to produce the initial and the last calculated stitch coordinates K, K' and Z, Z' which are specific from the intervening stitches as will be mentioned hereinlater.

CT₃ and CT₄ are counters which are reset at the time of application of the control power source or at the time of a pattern selection. The output Q₀ of the counter CT₁ is connected to the trigger terminal C_(p) of the counter CT₃ through the AND circuit AN₅, and is also connected to the trigger terminal C_(p) of the counter CT₄ through the AND circuit AN₆ and OR circuit OR₂, so that each high level signal at the output Q₀ may advance the count of the counter CT₃ or CT₄ while the movable contact (e) of the stitch mode changing switch is in engagement with the fixed contact (a₂) or (a₃). Comparators COMP₁, COMP₂ receive the outputs of the counters CT₃, CT₄, respectively. Each compare the input C₁ and the reference input Co=1 thereof and discriminate if the input C₁ is count 1 or not. If each input C₁ is count 1, the counters CT₃, CT₄ transmit the output P to the reset terminal R of the flip-flop FF₁ to reset the flip-flop through an OR circuit OR₁₀. Then the output Q₁ of the counter CT₁ is a high level. This enables the AND circuits AN₉, AN₈ to calculate out the second stitch coordinate so as to designate the input 1/2, or 1/3 of the constant generating device Ke while the fixed contact (a₂) or (a₃) of the stitch mode changing switch SW is effective. Thus, a constant is produced to determine the stitch coordinate K or K' shown in FIG. 1 or 2. In this connection, when the output Q₀ of the counter CT₁ is a high level, the output produce one of the stitches A-J in FIGS. 1 and 2, and the constant generating device Ke receives no input, and therefore gives no effective output.

Then the output Q₂ of the counter CT₁ becomes a high level for producing the third stitch L or L'. On the condition that the fixed contact (a₂) or (a₃) of the stitch mode changing switch SW is effective and/or that the flip-flop circuit FF₂ is set, the flip-flop FF₁ is set by way of an AND circuit AN₁₅ or AN₁₆ and by way of an OR circuit OR₁₁, and the true side output Q is connected to one input of AND circuits AN₁₁, AN₁₂ to designate the constant 3/4 or 2/3 of the constant generating device Ke each time the output Q₁ of the counter CT₁ becomes a high level and in accordance to the selection of the fixed contact (a₂) or (a₃) of the stitch mode changing switch SW. The flip-flop circuit FF₂ receives at the set terminal thereof a high level signal of the output Q₀ of the counter CT₁ through the AND circuit AN₅ or AN₆ and through the OR circuits OR₂, OR₃. The flip-flop FF₂ has a true side output Q connected to AND circuits AN₁₅, AN₁₆, and causes the AND circuit AN₁₆ to produce the output each time the output Q₂ of the counter CT₁ becomes a high level. Similarly, the flip-flop FF₂ designates the constant 1/4 of the constant generating device Ke through the AND circuit AN₁₀ each time the output Q₃ of the counter CT₁ becomes a high level while the fixed contact (a₂) of the stitch mode changing switch SW is selected.

The flip-flop circuit FF₂ has a reset terminal R for receiving the output of an AND circuit AN₁₇, so that the flip-flop may be reset just before the final calculated stitch Z or Z' in FIG. 1 or 2 is formed. The flip-flop FF₂ has a complement side output Q connected to the input side of AND circuits AN₁₃, AN₁₄ so as to designate the constant 1/2 of the constant generating device Ke through AND circuit AN₁₃ and OR circuit OR₇ when the output Q₃ of the counter CT₁ becomes a high level while the fixed contact (a₂) of the stitch mode changing switch SW is selected. Thus, the stitch coordinate Z in FIG. 1 is calculated out. Similarly, when the fixed contact (a₃) of the stitch mode changing switch SW is selected, the flip-flop circuit FF₂ designates the constant 2/3 through the AND circuit AN₁₄ and OR circuit OR₉ to calculate out the stitch coordinate Z' when the output Q₂ of the counter CT₁ becomes high level. On the other hand, when the fixed contact (a₁) of the stitch mode changing switch SW is selected, the counter CT₄ advances the count independently of the counter CT₁ through the OR circuit OR₂ each time the timing signal generating device SY produces a high level signal.

AR₃ is a calculating device for receiving the output of the counter CT₃ having a trigger terminal C_(p) for receiving a trigger signal together with output of the counter CT₃. The calculating device AR₃ seeks a value (n) as an address relation signal for the memory ROM from the formula n=2m-1, provided the value counted with the trigger signal is (m), and gives the calculated output to another calculating device AR₄ through a tristate buffer G₁₀. The calculating device AR₄ receives the output of the counter CT₄ through a tristate buffer G₁₁, and receives the value as an address relation signal (n) for the memory ROM which is counted by the counter CT₄ with the trigger signal. The calculating device AR₄ has a trigger terminal C_(p) for receiving a trigger signal through OR circuit OR₁₂ the trigger signal together with the buffers G₁₀, G₁₁ to selectively provide a outputs of the buffers G₁₀, G₁₁ are selectively received, so as a to provide a value (i) as an address signal for the memory ROM from the formula i=n-1, which value is applied to the pattern data read-out device DR through a tristate buffer G₁₂, the gate of which is simultaneously opened.

The pattern data read-out device DR selectively receives the outputs of the calculating devices AR₂, AR₄ as an address signal for the memory ROM in response to the trigger signal passing through the OR circuit OR₅ or OR₁₂. The device DR receives the signal of the pattern selecting device PS to designate the initial address of the memory ROM after it designates the last address of a pattern. The calculating device AR₂ receives the address signal (i) from the output A₂ of the memory ROM to make a calculation i=i+1. The memory ROM stores a data for the stitch coordinate J at the address 0 thereof for a selected pattern, for example, as shown is in FIGS. 1 and 2, and stores the data for the following stitch coordinates A, B, C . . . at the addresses 1, 2, 3 . . . . An initial address storing memory AL stores the address 0 when the memory AL receives a high level signal at the trigger terminal C_(p) thereof. Namely, when the output Q₀ of the counter CT₁ becomes a high level at the time of a pattern selection of a pattern, as is shown in FIGS. 1 and 2, the counter CT₃ or CT₄ counts 1 and makes 0 the address of the memory ROM and the input (i) of the memory AL. Simultaneously, the memory AL stores the signal i=0 with a high level signal at the true side output Q of the flip-flop FF₃ applied to the trigger terminal C_(p) of the memory AL, said flip-flop FF₃ being set by a high level signal of the monostable multivibrator circuit MM which is operated by way of the OR circuits OR₃, OR₄.

Comparator COMP₃ has an input connected to the output of the buffer G₁ or G₁₂, and compares the output with a reference signal Co, i.e. 0 of the memory AL to produce the output signal at the output P thereof when the output of the buffer G₁ or G12 comes in accord with the reference signal 0. The output signal of the comparator COMP₃ is high level and is given to an AND circuit AN₁₇ which receives the outputs Q₂, Q₁ of the counter CT₂ through AND-OR circuit. The AND-OR circuit has its inputs connected to the fixed contact (a₂), and to the fixed contacts (a₁), (a₃) of the stitch mode changing switch SW through OR circuit OR₁₃, and becomes a high level with a high level signal of the output Q₂ or Q₁ of the counter CT₂, to thereby reset the counters CT₃, CT₄ and the flip-flop circuits FF₂, FF₃ when one of the fixed contacts (a₁), (a₂), (a₃) is selected.

Namely, while the counter CT₂ is operated to advance the addresses of the memory ROM to read out a set of stitch control data prior to formation of a stitch as aforementioned, the reset condition of the counters CT₃, CT₄ and the flip-flop circuits FF₂, FF₃ designates the address 0 of the memory ROM, to thereby terminate the read-out of the final stitch control data of a pattern when the output Q₅ of the counter CT₂ becomes high level and simultaneously to return the control circuit to the initial condition, so as to repeatedly produce the stitches of the selected pattern.

AND circuits AN₁₈ -AN₂₃, each of which has one input connected to the output Q₅ of the counter CT₂, determine the opening time of the buffers G₂ -G₉, the latching time of the latch circuits L₁, L₂, L₃ and the output time of the calculating device AR₁ through the OR circuits OR₁₄ -OR₁₉ and the AND circuit AN₄ or directly. The AND circuit AN₁₈ has another input connected to the output of the OR circuit OR₃ to open the buffer G₃ when the output of the OR circuit is high level, and simultaneously to latch the data of the latch circuit Dn to the latch circuit L₁ through the OR circuit OR₁₉ and the AND circuit AN₄ and with the timing signal of the timing signal generating device SY, to thereby give the stitch forming device DV the initial data of the pattern. The AND circuit AN₁₉ has another input connected to the outputs of the AND circuits AN₁₁, AN₁₂ through the OR circuit OR₂₀ to latch the data of the latch circuit Dn-1 to latch L₂ and the data of the latch circuit Dn+1 to the latch circuit L₃, so that the calculating device AR₁ may make a calculation Ke·(L₃ -L₂)+L₁ with the data and the constant 3/4 or 2/3 of the constant generating device Ke at that time. Then the calculated effect is given to the stitch forming device DV through the latch circuit L₁ with the low level signal of the timing signal generating device SY.

The AND circuit AN₂₀ has another input connected to the outputs of the AND circuits AN₁₅, AN₁₆ through the OR circuit OR₁₁ to latch the data of the latch circuit Dn to the latch circuit L₂ and the data of the latch circuit L₃, so that the calculating device AR₁ may make the same calculation with the data and the constant 1/2 or 1/3 of the constant generating device Ke. The AND circuit AN₂₁ has another input connected to the output of the AND circuit AN₁₀ to latch the data of the latch circuit Dn+1 to the latch circuit L₂ and the data of the latch circuit Dn+3 to the latch circuit L₃, so that the calculating device AR₁ may make the same calculation with the data and the constant 1/4 of the constant generating device Ke. The AND circuit AN₂₂ has another input connected to the outputs of the AND circuits AN₈, AN₉, AN₁₄, through the OR circuit OR₂₁, to latch the data of the latch circuit Dn to the latch circuit L₂ and the data of the latch circuit Dn+1 to the latch circuit L₃, so that the calculating device AR₁ may make the same calculation with the data and the constant 1/3 or 1/2 of the constant generating device Ke. The AND circuit AN₂₃ has another input connected to the output of the AND circuit AN₁₃ to latch the data of the latch circuit Dn+1 to the latch circuit L₂ and the data of the latch circuit Dn+2 to the latch circuit L₃, so that the calculating device AR₁ may make the same calculation with the data and the constant 1/2 of the constant generating device Ke.

Referring now to FIG. 3, and FIG. 4 which shows the operation times of the circuit components with the output and triggering levels thereof for forming the stitches K-Z illustrated by the solid line in FIG. 1, the operation of the aforedescribed control circuit will be described.

If the control power source is applied at time (t₀) the counters CT₁ -CT₄, and the flip-flop circuits FF₁ -FF₃ are reset. The pattern selecting device PS is operated to select the original pattern of stitches A-J as shown in FIG. 1 or 2. The stitch mode changing switch SW is operated to close the fixed contact (a₂) to select the pattern of stitches K-Z, as shown in FIG. 1. The machine controller switch CONT is closed at time (t₁) to drive the sewing machine with a constant speed.

At the time (t₁), the counter CT₃ receives a high level signal through the AND circuit AN₅ and counts up 1 (which is to be represented by a letter m). The flip-flop circuit FF₁ receives a new reset signal through the comparator COMP₁ and the OR circuit OR₁₀. The calculating device AR₃ produces an output n=1 from the calculation n=2m-1. The calculating device AR₄ produces an output i=0 from the calculation i=n-1. The data read-out device DR gives the address i=0 to the memory ROM and to the initial address storing memory AL. The memory ROM produces the stitch control data A₁ in response to the address 0 determining the stitch coordinate J in FIG. 1, and produces the address signal A₂, i.e. i=0 to the calculating device AR₂.

On the other hand, the flip-flop circuit FF₂ is set through the OR circuit OR₃ at the time (t₁), and at the same time, the monostable multivibrator circuit MM is operated through OR circuit OR₄, and the flip-flop FF₃ is set. With the high level signal of the flip-flop circuit FF₃, the memory AL gives the data O to the reference data input terminal Co of the comparator COMP₃.

With the low level signal of the monostable multi-vibrator circuit MM at time (t₂), the latch circuit Dn-1 is triggered through the AND circuit AN₇ and latches the stitch control data J (A₁). A little later than the time (t₂), when the output Q₀ of the counter CT₂ is turned to a low level and the output Q₁ is turned to a high level, the calculating device AR₂ receives a trigger signal through the OR circuit OR₅ and makes a calculation i→i+1 and gives i=1 to the data read-out device DR and to the input terminal C₁ of the comparator COMP₃. At the same time, the data read-out device DR receives a trigger signal through the OR circuit OR₆ and makes 1 the address (i) of the memory ROM. Then the memory ROM produces the stitch control data A₁ for determining the stitch coordinate A in FIG. 1 and sends the address signal i=1 (A₂) to the calculating device AR₂.

At the time (t₂), the output signal of the OR circuit OR₅ operates the monostable multivibrator circuit MM through the OR circuit OR₄. At the time (t₃), when the output Q₁ of the counter CT₂ is turned to a low level due to the low level signal of the monostable multivibrator circuit MM, the latch circuit Dn latches the stitch control data A (A₁). In the same manner, at the times (t₄), (t₅), (t₆), the latch circuits Dn+1, Dn+2, Dn+3 latch the stitch control data B, C, D (A₁), respectively, with the outputs Q₂, Q₃, Q₄ of the counter CT₂ turned to a low level. When the output Q₅ of the counter CT₂ becomes a high level, the tristate buffer G₃ is opened by way of the AND circuit AN₁₈ to transmit the stitch control data A (A₁) of the latch circuit Dn to the latch circuit L₁.

Since the output of the AND circuit AN₁₈ turns one input of the AND circuit AN₄ to a high level, the latch circuit L₁ latches the stich control data A (A₁) with the low level signal of the timing signal generating device SY, to thereby enable the stitch forming device DV to form the initial stitch A in FIG. 1. Simultaneously, the output Q₀ of the counter CT₁ is turned to a low level and the output Q₁ is turned to a high level with the high level signal of the AND circuit AN₄. Actually, the operations of the counter CT₂ at the times (t₂)-(t₆) advance with a speed high enough to be stopped before the time (t₇).

When the output of the timing signal generating device SY becomes a high level at the time (t₈), the output Q₁ of the counter CT₁ opens the gates of the buffers G₄, G₆ through the AND circuit AN₉, OR circuit OR₂₁, AND circuit AN₂₂ and through the OR circuit OR₁₄ and OR circuit OR₁₆, to thereby give the stitch control data A and B (A₁) of the latch circuits Dn and Dn+1 to the latch circuits L₂, L₃ respectively, which latch these data with a trigger signal applied thereto through the OR circuit OR₁₈ to give the same data to the calculating device AR₁. Simultaneously, the output of the AND circuit AN9 designates the constant 1/2 of the constant generating device Ke through the OR circuit OR7 to give the out-put to the calculating device AR1. Then the calculating device AR1 makes a calculation Ke·(L3-L2)+L2=1/2 (B-A)+A for the next stitch K, and gives the calculated effect results to the latch circuit L1. At the time (t₉) with the low level signal of the timing signal generating device SY, the latch circuit L1 latches the stitch control data K and causes the stitch forming device DV to form the second stitch K in FIG. 1. Simultaneously, the output Q2 of the counter CT1 becomes a high level. The initial stitch A is formed at the center of the maximum needle swinging range, i.e., at the needle position of swinging amplitude 0. The second stitch K is formed at the needle position between the basic stitch A and the next basic stitch B with a half of the needle swinging amplitude between the stitches A and B, in accordance with the calculation of the calculating device AR1.

In the same manner, at the time (t₁₀), the output Q2 of the counter CT1 sets the flip-flop circuit FF1 through the AND circuit AN15 and OR circuit OR11 and opens the gates of the buffers G4, G7 through the AND circuit AN20 and OR circuits OR14, OR17, to give the stitch control data A and C (A1) of the latch circuits Dn, Dn+1 to the latch circuits L2, L3, respectively. Then the latch circuits L2, L3 latch the same data, respectively, so as to give the same to the calculating device AR1. Simultaneously, the output of AND circuit AN15 designates the constant 1/2 of the constant generating device Ke through the OR circuit OR7 to give the constant to the calculating device AR1. The calculating device AR1 makes a calculation Ke·(L3-L2)+L2=1/2(C-A)+A for the next stitch L and gives the calculated result to the latch circuit L1. At the time (t₁₁), the latch circuit L1 latches the stitch control data L to cause the stitch forming device DV to form the third stitch L. Simultaneously, the output Q3 of the counter CT1 is turned to a high level.

At the time (t₁₂), the output Q3 of the counter CT1 designates the constant 1/4 of the constant generating device Ke through the AND circuit AN10, opens the gate of buffer G5 through the AND circuit AN21 and OR circuit OR15 and opens the gate of buffer G8 through the AND circuit AN21, so as to give the data B and D of the latch circuits Dn+1, Dn+3 of the latch circuits L2, L3 respectively. The latch circuits L2, L3, latch the same data, respectively, so as to give the same to the calculating device AR1. The calculating device AR1 makes a calculation Ke·(L3-L2)+L2=1/4(D-B)+B for the next stitch M and gives the calculated effect to the latch circuit L1. At the time (t₁₃), the latch circuit L1 latches the data M to cause the stitch forming device DV to form the fourth stitch M. Simultaneously, the output Q4 of the counter CT1 is turned to a high level and is reset by way of the AND circuit AN1 and OR circuit OR1. As a result, the output Q0 of the counter CT1 is turned to a high level, and then the output Q0 of the counter CT2 becomes high level.

As is seen, the calculating device AR1 employs the constant 1/2 for making a calculation to produce the stitches K and Z while employing the constants 1/4, 3/4, i.e., 4-divided constants for making the calculations to produce the stitch M and the following stitches on the left side of the pattern. Namely, in FIG. 1, the stitches A and B for calculating the stitch K are formed with a fabric feeding pitch which is a half of that between the stitches B and D, D and F, . . . . On the other hand, the calculating device AR1 employs the constants 1/2 for making a calculation to produce the stitches L, O, R . . . on the right side of the pattern. This is because the needle is initially deflected to the left from the stitch A. These stitches L, O, R, . . . formed when the needle is deflected to the right from the stitches K, N, Q . . . respectively are positioned opposite to the basic stitches B, D, F, . . . .

At the time (t₁₄) when the signal of the timing signal generating device SY becomes a high level, the counter CT3 is operated to count up to make m=2. Then the calculating device AR3 makes a calculation n=2m-1=3 and the calculation i=n-1=2 to designate the address 2 of the memory ROM. In the same manner, the address of the memory ROM is advanced to 3, 4, . . . from the address 2 in accordance with the count-up of the counter CT2, and the latch circuits Dn-1, Dn . . . , Dn+3 latch the data B, C, . . . F, respectively. At the time (t₂₀), the latch circuit L1 latches the data C to cause the stitch forming device DV to form the fifth stitch C.

At the time (t₂₁), the output Q1 of the counter CT1 designates the constant 3/4 of the constant generating device Ke through the AND circuit AN11 and opens the gate of buffer G2 through the OR circuit OR20 and AND circuit AN19, and also opens the gate of buffer G6 through the OR circuit OR16 to give the data B, D of the latch circuits Dn-1, Dn+1 to the latch circuits L2, L3, respectively. These latches L2, L3 latch the same data to give the same to the calculating device AR1. The calculating device AR1 makes a calculation Ke·(L3-L2)+L2=3/4(D-B)+B and gives the calculated effect to the latch circuit L1. At the time (t₂₂), the latch circuit L1 latches the data N to cause the stitch the data N to cause the stitch forming device DV to form the sixth stitch N.

In the same manner, the following stitches are formed one after another. When the sixteenth stitch H is formed, and the output Q0 of the counter CT1 is turned to a high level, the counter CT3 is operated to count to make m=5. The calculating device AR3 makes a calculation n=2m-1=9, and the calculating device AR4 makes a calculation i=n-1=8 to designate the address 8 of the memory ROM. As the counter CT2 counts, the address of the memory ROM is advanced to 9, 10 . . . from the address 8, and the latch circuits Dn-1, Dn . . . Dn+3 latch the data H, I, J, A, B respectively. In this process, when the output Q2 of the counter CT2 is turned to a high level, the calculating device AR2 is i=0, and therefore the output P of the comparator COMP3 is a high level and the AND circuit AN17 is a high level due to the input thereof from the AND-OR circuit, to thereby reset the counters CT3, CT4 and the flip-flops FF2, FF3. With the following low level signal of the timing signal generating device SY, the seventeenth stitch I is formed and the output Q1 of the counter CT1 is turned to a high level.

The eighteenth stitch X is formed with the calculation by way of the AND circuit AN11 and with the following low level signal of the timing signal generating device SY, and then the output Q2 of the counter CT1 is turned to a high level.

The nineteenth stitch Y is formed with the calculation by way of the AND circuit AN15 and with the following low level signal of the timing signal generating device SY, and then the output Q3 of the counter CT1 is turned to a high level.

The twentieth stitch Z is formed with the calculation by way of the AND circuit AN13 and with the following low level signal of the timing signal generating device SY, and then the output Q4 of the counter CT1 is turned to a high level. Then the counter CT1 is immediately reset and the output Q0 is turned to a high level. With the following high level signal of the timing signal generating device SY, the count-up of the CT3 returns to the time (t₁), and the pattern is repeatedly produced.

Now if the fixed contact (a3) of the stitch mode changing switch SW is closed to select the pattern of stitches A, K', L', B, M' . . . Z', illustrated by a solid line in FIG. 2, the counter CT4 and the comparator COMP3 are operated, instead of the counter CT3. The counter CT4 is operated to count each time the output Q0 of the counter CT1 becomes a high level and gives the value (n) to the calculating device AR4, so that the calculating device AR4 may make a calculation i=n-1. The counter CT1 is reset when the output Q3 is turned to a high level, and the output of the counter is transmitted to the calculating device AR1 through the AND circuit AN8, AN12, AN14, AN16, so that a series of data controls may be implemented as was implemented in the production of the pattern stitches of FIG. 1.

On the other hand, if the fixed contact (a1) of the stitch mode changing switch SW is closed to select the original pattern of stitches A-J shown in FIG. 1 or 2, the counter CT4 counts up n=1 at the time t₁, and the latch circuits Dn-1 to Dn+3 latch the data J, A, . . . D, respectively. The initial stitch A is formed at the time (t₇), and then the output Q1 of the counter CT1 becomes high level. The counter CT1 is reset at the time (t₈) through the OR circuit OR1. Therefore, the other outputs of the counter CT1 will not be turned to a high level, and the AND circuits AN8, AN9, AN11, AN12 receiving the output Q1 of the counter CT1 will not be turned to a high level because these AND circuits are connected to the fixed contact (a2) or (a3) and not to the contact (a1) of the stitch mode changing switch SW. Therefore, the AND circuits AN10 to AN23 will not be turned to a high level, and only the data of the latch circuit Dn is latched to the latch circuit L1. The data of the other latch circuits Dn-1, Dn+2, Dn+3 are not used. The counter CT2 is reset with a high level output Q0 of the counter CT1 at the time (t₈), and the data of the latch circuits Dn-1 to Dn+3 are changed immediately after the time (t₁₄ ). Namely, at the time (t₈), the counter CT4 counts up n=2 to designate the address 1 of the memory ROM to read the data A. With the subsequent operations of the counter CT2, the latch circuits Dn-1 to Dn+3 latch the data A to E, respectively, and the data B of the latch circuit Dn is latched to the latch circuit L1 and the second stitch B is formed.

In the same manner, the stitches C, D, . . . I are formed one after another, and the counter CT4 counts up n=10 with the subsequent high level signal of the timing signal generating device SY and the address 9 of the memory ROM is designated. Then the latch circuits Dn-1, Dn . . . Dn+3 latch the data I, J, A, B, C, respectively. In this process, the counter CT4 is reset with the output of the comparator COMP3. With the subsequent low level signal of the timing signal generating device SY, the tenth stitch J is formed. With the next high level signal of the timing signal generating device SY, the counter counts up n=1. Thus, the control circuit is returned to the initial condition for repeatedly forming the pattern.

While the invention has been illustrated and described as embodied in an electronic sewing machine, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention. 

What is claim as new and desired to be protected by Letters Patent is set forth in the appended claims:
 1. A sewing machine having a rotatable shaft means for operating a stitch forming device and including feed dog means for feeding a fabric to be sewn and a needle for forming stitches in the fabric, the machine comprising:(a) first electronic memory means (ROM) for storing stitch control data, said first memory means including at least the needle position control data for different positions; (b) pattern selecting means for reading out from said first memory said stitch control data for a selected pattern; (c) timing means (SY) operated synchronously with said shaft means to produce a timing signal for progressively reading out said stitch control data from said first memory; (d) stitch mode changing switch means (SW) selectively operated to determine an elongation rate of a selected pattern to be elongated in a feeding direction; (e) second memory means (Dn-1 to Dn+3) for temporarily storing designated stitch control data of said first memory means; (f) counter means (CT1, CT2) for counting the ordinals of stitches of a selected pattern in relation to a timing signal of the timing means and in accordance with said pattern elongation rate determined by the stitch mode changing means, to thereby designate the pattern elongation rate and the stitch control data to be stored in said second memory means progressively during formation of the stitches of said pattern; and (g) calculating means (AR1,Ke) operable with respect to an output of said counter means to make a calculation to produce different stitches between the stitches which are formed by the stitch control data stored in the second memory means.
 2. The sewing machine as recited in claim 1 wherein said pattern selecting means includes pattern selecting switches, said switches being operable to read out from said first memory means.
 3. The sewing machine as recited in claim 1, wherein said calculating means includes a predetermined number of constants, said calculating means being operated with respect to a counted output of said counter means so as to make said calculation by selectively using said constants and said needle position control data of said stitch control data stored in said second memory. 